crystallograph
by justjoy
Summary: In most regards, Ai supposes, she could have done worse than having the Kaitou Kid as her soulmate. [for the prompt: soulmate!AU, KaiShi.]


soulmate!AU requested by mintchocolateleaves, with Kaito/Shiho: _the one where once you meet your soulmate, it's physically uncomfortable to be apart from them for too long._

 _this turned out more ai-centric than anything else lmao, mea culpa. scenes not in chronological order, will probably rework/expand later bc i feel 70% happy with this one but have it anyway for now or i'll never post it rip_

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 **v.**

In most regards, Ai supposes, she could have done worse than having the Kaitou Kid as her soulmate.

It might've been Edogawa instead, for starters, and while that isn't in itself a problem it'd still mean seeing more dead bodies than she really cares for.

(Though if Kuroba tries to talk her into moving to Ekoda _again_ , Ai isn't going to be responsible for what she does in response.

It's mostly his fault that they ever met anyway, so as far as she's concerned he can either move to Beika or deal with the consequences.)

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 **iv.**

Shiho has never put much stock in the concept of soulmates.

She's well-acquainted with the scientific evidence, obviously. Extensive research in the field continues to be ethically controversial, but studies have sufficiently demonstrated the correlation between separating certain pairs of people for extended periods of time and the associated physiological effects: increased heart rate, shallow respiration, heightened levels of cortisol. The evidence is convincing, though the particulars differ, and no rigorous theory of the bond has been developed thus far.

What she questions are the psychological effects people often discuss. Nothing ludicrously precise as telepathy – those claims had been thoroughly debunked in the '80s, even if urban legends still circulated to this day – but instead a whole host of subtler effects, with the most commonly cited one being empathy connected to strong feelings.

It seems fallacious, though, to assume that such a bond would entail any emotional connection, beyond the effects of cognitive dissonance working to smooth over a relationship enforced by proximity.

At any rate, as far as Shiho's concerned, her soulmate – _if_ she has one, since the conditions make it difficult to conclusively prove whether or not every individual has a soulmate – is better off staying away from her, for both their sakes. The last thing she needs is to be bound down geographically, let alone to any single individual, and unless her hypothetical soulmate is in the Organisation as well she doesn't see how the situation can be tenable anyway.

(She rarely spends time around people anyway, so it's not like it matters all that much, really.)

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 **iii.**

If nothing else, being an elementary schooler means that people assume by default that she hasn't really thought much about the concept of soulmates yet, let alone had a chance to meet her own.

Ai is more than fine with that. She still believes that the entire phenomenon of soulmates is more trouble than it's worth, and becoming Haibara Ai has only served to further cement that opinion, if anything.

(The professor had asked her about it once, near the beginning, followed a few days later by Edogawa when he'd stopped tiptoeing around her like a bomb set to explode at any moment. The detective hadn't bothered couching it as an indirect question, of course, but she understood the intent all the same, as well as their relief when she'd answered in the negative.

You couldn't very well sever a bond with just a change of name, after all, and Edogawa is very fortunate that Mouri Ran isn't his soulmate, because there wouldn't have been any hiding from that.)

.

 **ii.**

Akemi doesn't share her opinions, of course.

Shiho watches her sister talk animatedly over dinner, eyes alight with excitement, about an old school friend of hers who'd just found her soulmate, and wonders if she should hope for Akemi to find her own as well.

(Sometimes, she wishes that she'd thought to ask.)

.

 **i.**

Ayumi and the others are chatting about soulmates during lunch break one day, Edogawa chiming in every now and then with the occasional correction when their chatter veers too far from the facts, when Genta asks, "How d'you even know so much about soulmates anyway, Conan-kun?"

Edogawa laughs in the way he does whenever he's trying to redirect someone's attention. "Ah, Ran-neechan and Sonoko-neechan talk a lot about it, that's all!"

The kids nod, satisfied by this answer, but it's like a switch flicks on in Ai's mind – because Genta has a point, and Ai can't believe she hasn't noticed it before.

She knows almost everything Edogawa has mentioned so far, that much is true, but that's largely because she'd just about gone through the existing literature with a fine-toothed comb to check for anything that could potentially interfere with the apoptoxin's effects.

Even so, Edogawa's mentioned details that even Ai herself isn't aware of, and while she _can_ testify to the fact that teenagers talk incessantly about the possibility of meeting their soulmates, as far as she knows neither Mouri nor Suzuki have found theirs yet.

She does at least wait until they're out of the Detective Boys' earshot before asking the increasingly apparent question. "You _do_ have a soulmate, don't you, Edogawa-kun?"

He's clearly prepared for it, though, because he doesn't even hesitate before answering. "I told you, Ran's not my soulmate."

…Edogawa is a _terrible_ liar. Nevertheless, Ai looks away, pretending to drop the subject as she thinks – it _has_ to be someone in the know, and the answer is startlingly obvious once she thinks about it.

Ai can feel herself smirking. She can't help it. "So, how is it, having Hattori-kun as a soulmate?"

 _That_ makes Edogawa choke on the orange juice he's drinking, which is all the confirmation she needs. Serves him right for forgetting that he's not the only one capable of detective work here, Ai thinks with vindictive satisfaction.

(Then, of course, Ayumi manages to convince her to attend a Kid heist less a week later, and – well.

Ai believes in karma even _less_ than she does soulmates, but the irony is almost enough to convince her otherwise.)

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 **0.**

The rooftop is _freezing._

It's not snowing, at least, but the gusts of biting wind aren't much of an improvement.

Today's heist is the third she's attended so far, though Ayumi had still been surprised when Ai said that she was planning on coming along – she'd promptly proceeded to power excitedly through the afternoon's classroom cleaning, dragging the boys along in her wake.

(Ai had ignored Edogawa's obviously amused glances all the way to the heist site. His deductions aren't completely off-track, after all, since she _is_ developing an interest in Kid, if not for the reasons he apparently assumes.

It's not at all surprising for an elementary schooler to be a Kid fangirl, after all, and Ai's been careful to cultivate her attention gradually enough to avoid suspicion.

At any rate, it's almost a blessing in disguise that Ai's bonded to one of the few people even less likely than herself to want a soulmate known. Kid, at least, might not have enemies that would cheerfully take a soulmate ransom if given the chance, but Ai isn't planning on taking risks either way.)

She tightens the scarf around her neck, grateful that she'd thought to dress in warmer clothing today, and tries to occupy her thoughts with figuring out whether she can gauge Kid's proximity from how she's feeling.

As a distraction from the weather, it's resoundingly unsuccessful, but her mental map narrows abruptly just as Kid slips through the roof access door, jams the lock firmly closed, and turns towards her.

(His cape flares dramatically with the motion. Ai gives him an unimpressed look.)

"Good evening, ojousan." The magician doesn't sound surprised, but that means little for someone who isn't fazed by Edogawa's soccer missiles. "Should I assume that your presence means what I believe it does?"

"I certainly hope so," Ai says, her tone perhaps more curt than the situation calls for, but she's been waiting for a long time and it is _cold._ "You might not agree, but I'd hate to be stuck with someone of subpar intelligence."

Amusement flickers across Kid's expression. "That's a tall order, but I'll do my best. Does tantei-kun know?"

It's a question Ai expects, so her answer comes readily enough. "I haven't told anyone, but I'd give it three weeks at most before he figures it out, though the sheer unlikelihood of this situation might throw him off for a while longer. Either way, I don't have any plans to assist Edogawa-kun in catching you with this, to answer your actual question."

"The inadmissibility of soulmate bonds as evidence in court notwithstanding, I suppose?" Kid asks lightly, and Ai shrugs. It's not like either of them actually believe that the detective would do anything based on such a tenuous thing without amassing further evidence, anyway.

"If you get caught on your own, that's frankly none of my business," she replies blithely, crossing her arms. "Though at least you'd have a regular visitor in prison, if that's any consolation."

Kid hums noncommittally as he holds tonight's heist target up to the moonlight. "Not that I wouldn't appreciate the company, hypothetically speaking, but if you could consider bringing chocolate?"

Ai raises an eyebrow – she hadn't pegged the magician to be a chocoholic, though perhaps she _should_ have, assuming that he kept up an active civilian life alongside his night persona – when there's the recognisable crackle of Edogawa's shoes powering up in the near distance.

Kid somehow manages to cross the span of the rooftop in the few seconds it takes for a soccer ball to force the door open, revealing Edogawa behind it, dart watch already aimed and ready to fire.

Before the detective can say anything, though, Kid smirks visibly under the shadow of his hat and speaks, loud enough to be heard over the wind even from several metres away. "Looks like you got beaten to the punch this time, tantei-kun!"

Edogawa glances over at her in disbelief, though his watch doesn't waver from its target. " _Haibara?_ How'd you manage to get up here so quickly?"

"Wouldn't _you_ like to know, meitantei-san?" Ai quips right back, already turning to leave. "I'd be more worried about your quarry getting away if I were you, though."

The detective blanches at the reminder and turns back immediately, but Ai doesn't need to look over her shoulder to know that Kid's used the distraction to slip away – on his glider, probably, from the vague sense of steadily increasing distance between them.

She tucks her hands back into the welcome warmth of her coat pockets as she glances up anyway, her gaze tracking the white triangle across the night sky.

"Better luck next time, Edogawa-kun," Ai says with a complete lack of sincerity, and leaves him alone on the rooftop, staring after her in confusion.

(She doesn't miss the smooth edges of a card in her right pocket, of course, but waits until Agasa fetches them home before taking it out.

Black ink stands out starkly against the plain rectangle even in the dim moonlight – one sentence followed by a Kid caricature:

 _Don't be a stranger!_ O_

Ai rolls her eyes – if Kid _is_ actually expecting her to follow him across town he's got another think coming – before putting the card away in her top drawer and locking it.

The feeling from earlier is faint now, not registering as discomfort so much as an indefinable pressure, but as far as she can tell, Kid has mostly stopped moving some considerable distance away, though she can't pick out the direction he's in.

The scientist in Ai is increasingly tempted to study the boundaries of this, now that she has herself as an immediately accessible test subject, but she contents herself with the one experiment she can run immediately.

Ai silences her other thoughts as completely as she can, and focuses her mind on one sentence.

 _Don't_ _leave your heist targets with me,_ Ai thinks, emphatically, with all the annoyed exasperation the sentiment deserves.

She's fully planning to drop the jewel in Edogawa's school satchel once she gets the chance, obviously – no one needs to know that it was in her left pocket at some point, and it wouldn't be the first time a heist target has been returned to Nakamori-keibu via detective.

But still. It's the principle of the matter, and if Ai has no choice but to attend Kid heists regularly now she's going to do it on her own terms.)

.

("Are you alright, Kaito-bocchama?" Jii asks in concern when Kaito shivers, and he can only shrug cluelessly in response – the Blue Parrot is warm, the chocolate in his mug more so.

None of it explains why he'd felt a sudden chill down his spine, unless Akako is up to something again.

Kaito _really_ hopes she isn't.)

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 **END...?**


End file.
